Access to a computing system's settings and controls are typically presented to a user via a collection of individual user interactive applications collected for presentation within a control panel user interface. The computing system's settings and controls are coded with a programmable means for user interaction at the user interface.
FIG. 1 shows a computing system 100 having a conventional control panel user interface. Computing device 100 has a display 110 and a base 112. The base 112 contains memory 114 that stores systems applications 116 and 118(A1-AN).
A user interface (UI) 120 is shown displayed on the computing device display 110. In FIG. 1, the UI 120 is embodied as the control panel 130 in the familiar “Windows”-based operating system from Microsoft Corporation. Control panel 130 presents a user with a multitude of selectable application control icons 132(I1-IN) that expose both simple and complex system configuration settings and controls at the same level. Each application icon 132 is independently associated with a system application 118 within the computing device memory 114 (e.g., icon I1 is the independent UI associated with application A1, and so forth).
The presentation of control panel 130 is controlled by system application 116. Each systems application 118 is associated with the presentation of a control panel UI, and is also integrated with the presentation of the control panel 130 in conjunction with the control panel system application 116.
From a user standpoint, multiple unrelated system control panels make it difficult for a user to locate a system setting or control that he or she wants to change. Furthermore, related settings and controls are separated into different control panels, causing a user to have to search the various control panels to accomplish a set of related settings and control tasks.
Accordingly, there is a need for control panel UIs that enables a user to easily navigate a computing system's settings and controls. Additionally, there is a need for an extensible UI presentation technique that enables a developer to easily design, modify, and replace control panel UIs.
New computing display and data presentation techniques have developed as a result of the Internet and the fast-paced technological advancements in computing and user interaction. One such presentation and display technology utilized by developers of Internet Web pages is Hypertext Markup Language (HTML) in conjunction with Extensible Markup Language (XML). Many readers will be familiar with HTML and XML. However, to provide additional background, the following discussion presents an overview of the conventional HTML and XML technologies.
Hypertext Markup Language
Hypertext Markup Language (HTML) is a display language for presenting data to an end user in a visual presentation. Internet Web pages are commonly written in HTML and may include text, images, sound, video, active code, and so forth. Data binding is an aspect of Dynamic HTML (DHTML) that allows processing individual items of data from an information source into an HTML display, thus allowing HTML to be used as a template for displaying the data, while creating an extensible and interactive Web page. DHTML allows a developer to individually manipulate any HTML page element at any time.
Making simple updates to an HTML page, such as changing the color of text after a Web page has been rendered for display, typically requires reloading the entire page to account for the one desired change. With DHTML, however, every element within the page is independently dynamic and an individual element (text or graphics) can be changed without having to reload the entire page.
Extensible Markup Language
Extensible Markup Language (XML) is a meta-markup language that provides a format for describing structured data. XML is similar to HTML in that it is a tag-based language. By virtue of its tag-based nature, XML defines a strict tree structure or hierarchy. XML is a derivative of Standard Generalized Markup Language (SGML) that provides a uniform method for describing and exchanging structured data in an open, text-based format. XML utilizes the concepts of elements and namespaces. Compared to HTML, which is a display-oriented markup language, XML is a general purpose language for representing structured data without including information that describes how to format the data for display.
Internet Web-based data viewing is typically enabled via XML data that is stored on a server at an Internet site. The XML data is transferred to a client device upon request and rendered for viewing with HTML. An XML document does not by itself specify whether or how its data should be displayed. The XML data is merely the factual information to be displayed.
An unique attribute of utilizing XML structured data is that the data is separated from the HTML presentation to a user. While HTML specifies how to display data in an Internet browser, XML only defines the content data to be displayed. HTML utilizes tags to specify how an Internet browser will display the data (i.e., bold or italic). In XML, tags are only used to describe the data (i.e., a title name), and not to specify how the data will be displayed. To describe how the data will be presented, XML references a separate application or stylesheet.
Extensible Stylesheet Language
Extensible Stylesheet Language (XSL) provides both the semantic and structural independence for presenting the content of XML data. A style sheet contains a template of the desired structure for data presentation, and identifies the data in an XML source document to insert into the template. Thus, the XML data is separated from the presentation, allowing both the grammar and the structure of the XML source document to be independent of the presentation language and the structure.
XSL style sheets contain instructions for presenting the data in an XML document in a format such as HTML. XML enables data to be processed and displayed by applying different stylesheets and applications while separating the data from the presentation and the process. The separation of the data from the presentation allows for a seamless integration of data from diverse sources. This further allows data encoded in XML to be easily exchanged on-line and delivered over the Internet to a client device.
FIG. 2 shows the components for transforming XML-based data into an HTML display using XSL. The HTML presentation system 200 includes an Internet server 202 and a requesting client device 204. The Internet server 202 includes XML data 210, an XSL template 212, and an XSL processor 214. The XML data 210 is processed with the XSL template file 212 at the XSL processor 214 to generate and present an HTML document 216 at the client device 204.
XML Structure
XML “elements” are structural constructs that consist of a start tag, an end or close tag, and the information or content that is contained between the tags. A “start tag” is formatted as “<tagname>” and an “end tag” is formatted as “</tagname>”. In an XML document, start and end tags can be nested within other start and end tags. All elements that occur within a particular element must have their start and end tags occur before the end tag of that particular element. This defines a strict tree-like structure. Each element forms a node in this tree, and potentially has “child” or “branch” nodes. The child nodes represent any XML elements that occur between the start and end tags of the “parent” node.
Namespaces in XML structured data qualify element names in a recognizable manner to avoid conflicts between elements with the same name. Namespaces ensure that element names do not conflict, and they clarify who defined which term. They do not give instructions on how to process the elements, but simply keep the names straight. Thus, XML namespaces convey meaningful information by associating a descriptive namespace with a tag name.
Within an XML document namespace declarations occur as attributes of start tags. Namespace declarations are of the form “xmlns:[prefix]=[uri]”. A namespace declaration indicates that the XML document contains element names that are defined within a specified namespace or schema. A “prefix” is an arbitrary designation that will be used later in the XML document as an indication that an element name is a member of the namespace declared by a universal resource indicator (uri). The prefix is valid only within the context of the specific XML document. A uri is either a path to a document describing a specific namespace or schema, or a globally unique identifier of a specific namespace or schema. A uri is valid across all XML documents. Namespace declarations are “inherited”, which means that a namespace declaration applies to the element in which it was declared as well as to all elements contained within that element.
Namespace inheritance within an XML document allows non-qualified names to use “default” namespaces. Default namespaces are explicitly declared as attributes of start tags. Default namespace declarations are of the form “xmlns=[uri]”. Note that the declaration of a default namespace is equivalent to the declaration of a non-default namespace but the prefix is omitted. A namespace specification within an XML document is said to have a “scope” which includes all child nodes beneath the namespace specification.
An example of XML code follows:
<trans:orders xmlns:person=“http://www.schemas.organization/people”xmlns:dsig=“http://www.dsig.org”xmlns:trans=“http://www.schemas.org/transactions”><trans:order><trans:sold-to><person:name><person:last-name>Layman</person:last-name><person:first-name>Andrew</person:first-name></person:name></trans:sold-to><trans:sold-on>1997-03-17</trans:sold-on><dsig:digital-signature>1234567890</dsig:digital-signature></trans:order></trans:orders>
This code includes three XML namespace declarations that are each designated with “xmlns”. The declarations include a prefix (e.g. “person”, “trans”, and “dsig”) and the expanded namespace to which each prefix refers (e.g. “http://www.schemas.org/people”, “http://www.schemas.org/transactions”, and “http://www.dsig.org”, respectively). This code tells any reader that if an element name begins with “dsig” its meaning is defined by the “http://www.dsig.org” namespace. Similarly, elements beginning with the “person” prefix have meanings defined by the “http://www.schemas.org/people” namespace and elements beginning with the “trans” prefix have meanings defined by the “http://www.schemas.org/transactions” namespace.
It is important to note that another XML document that incorporated elements from any of the namespaces included in this sample might declare prefixes that are different from those used in this example. As noted earlier, prefixes are arbitrarily defined by the document's author and have meaning only within the context of the specific element of the specific document in which they are declared. Tags from multiple namespaces can be mixed to accommodate data coming from multiple sources. With namespaces, two elements can exist in the same XML-based document, but can refer back to two different schemas, uniquely qualifying their semantics.
XML Schemas
XML accommodates an infinite number of database schemas and elements referenced in one XML document can be defined in different schemas. XML schema are typically implemented within a Web browser such as Internet Explorer from Microsoft Corporation to provide support for coinciding sub-sets of XML data. An XML schema specifies the structure of an XML document and the constraints on the document's content.
Specifically, a schema defines the elements that can appear within an XML document and the attributes that can be associated with an element. While defining the structure of an XML document, a schema also defines which elements are child elements of others, the sequence in which the child elements can appear, and the number of child elements. A schema further defines whether an element is empty or can include text, as well as defining default values for attributes. Overall, a schema is utilized to validate the content of an XML document and to determine whether an XML document is a valid instance of the grammar expressed by the schema.
Within each schema, a “dictionary” of element names is defined. The dictionary of element names defined by a schema is referred to as a “namespace.” Within an XML document, element names are qualified by namespace identifiers. When qualified by a namespace identifier, a tag name appears in the form “[namespace]:[tagname]”. This model enables the same element name to appear in multiple schemas, or namespaces, and for instances of these duplicate element names to appear in the same XML document without colliding. Start tags can declare an arbitrary number of “attributes” which declare “property values” associated with the element being declared. Attributes are declared within the start tag using the form “<[tagname] [attribute1],[attribute2] . . . ,[attributeN]>”, where attribute1 through attributeN are declarations of an arbitrary number of tag attributes. Each attribute declaration is of the form “[attributeName]=[attributeValue]” where each attribute is identified by a unique name followed by an “=” character, followed by the value of the attribute.
A schema is primarily the formal specification of the elements and attributes allowed within a particular class of XML document, and the schema specifies how those elements and attributes are related to each other. Elements and attributes are defined in an XML schema document by specifying an <ElementType . . . > and <AttributeType . . . >, respectively. These provide the definition and type of the element or attribute. An instance of an element or an attribute is declared using <element . . . > or <attribute . . . > tags. An example of an XML schema is shown following:
<?xml version=“1.0”?><Schema xmlns=“schemas-microsoft-com:XML-data”><ElementType name=“title”/><ElementType name=“author”/><ElementType name=“pages”/><ElementType name=“book” model=“closed”><element type=“title”/><element type=“author”/><element type=“pages”/><AttributeType name=“copyright”/><attribute type=“copyright”/></ElementType></Schema>
In this example, there are four <ElementType> defining elements: “title,” “author,” “pages,” and “book.” Within the ElementType for “book,” the content model for a book can be declared. Each book contains “title,” “author,” and “pages” elements using the <element> with a type attribute that references the ElementType. An <AttributeType> for the copyright attribute can also be defined and then its usage declared using the <attribute> element with a type attribute that references its definition.
The definition of the copyright attribute is contained within the ElementType for “book.” Attribute definitions are distinct from ElementType definitions in that they can be declared within the scope of an ElementType, allowing different element types to declare attributes of the same name but with potentially different meaning. <AttributeType> elements can be declared globally by placing them outside of the context of an ElementType. In this way, multiple elements can share the definition of a common attribute without having to redeclare the AttributeType within each ElementType.